Gordon Research Conferences on Mammary Gland Biology are planned for May 2004, June 2005 and May 2006 at Il Ciocco, Italy (2004 and 2006), and Roger Williams University, Bristol, RI (2005). These meetings encompass both basic mammary gland biology and breast cancer. These topics are currently the focus of intense investigation given the alarming rate of occurrence of breast cancer in the US and the western world. Furthermore, the benefits of breast feeding for both the infant and mother is becoming more apparent and the biology of lactation is of major importance in the dairy industry. Conference programs will represent the core of important new and ongoing research in mammary gland and cancer biology and will be designed specifically to foster interaction between investigators across disciplines. Participants and speakers will be drawn from academia and government research agencies, the medical profession and the biotechnology and pharmaceutical industries. The program for 2004 includes an opening presentation on p53 and cancer. Other sessions with a breast cancer focus will cover diet and other risk factors (including hormones) and mouse models. The rapidly emerging areas of stem cell research and embryonic development will be the focus of two sessions early in the meeting. We have introduced a new concept for this GRC meeting- an entire session devoted to young investigators working in the apoptosis field. This session will be chaired by a world leader in apoptosis research. Other sessions include cell fate determination via different families of signaling molecules such as Notch, SOCS and axonal guidance factors and the molecular biology of lactation and milk production in other species. The closing session will encompass the keynote address, which will present the exciting challenges facing mammary gland and breast cancer investigators. All partcipants will be able to present posters and attend a workshop on imaging technology in mammary biology. Subsequent meetings planned for 2005 and 2006 will focus on current developments in the field. The Mammary Gland Biology Gordon Research Conference is the premier conference in the field and is an essential mechanism for promoting interactions between investigators interested in all aspects of breast biology from molecular biology, to tumorigenesis, endocrine function, and lactation.